Hydraulic jack



- The present application is, a continuation "in I Patented Mar 1933 nimn! w. nomms, 01' IN I it" nin'maumc nor Application filed November 22,1928. Serial llo. 821,188.

This invention relates to an improvement in hydraulicjacks especially adapted for use with motor vehicles although also well adapted for various other uses and: applicatlons.

part of the co-pending application of Harry W. Bolens for hydraulic jacks filed July 20, 1927, Serial No, 207,129, now Patent- No. 1,709,000, granted April 16, 1929.

Various types of hydraulic jacks are coming into use at the resent time, but all of them comprise essenti y a base carrying a jack cylinder or lifting c linder in which the ram or lifting piston oft e jack is fitted. A manoperable .pump is also provided-and is elements of the hydraulic jack have been or-' .iLficult gnd expensive machinin ofthis kind as it is essential to keep utihzed for transferring a liquid, such as oil,

from the reservoir to the lifting cylinder and beneath the lifting piston thereof. Avalve controlled bypass 1s also provided for permitting return flow of the liquid from the cylinder to the reservoir when the jack is being lowered. While these essential fundamentalgamz'ed in many diferent ways, the present invention is applicable to practically any organization thereof in that it has to deal with the range of action of the lifting piston and the retnrnof the liftin piston to lowered or inoperative position. t-will'be'readily appreciated that the size of a hydraulic jack;

is necessarily limited, when it is intended for I use ivith the cpresent. types of motor-vehicles, arance between the art'of the,

by the road vehicle which the 'ack engage .and the a and. Thisroad c earance varies with diferent vehicles and to render a hydraulic jack capable of advantageoususe with difierent types of vehicles, it has been pro sed extension, usually n the formvof a screw,

- which is normally housed in the hollow lifting piston, but which maybe extended therefrom as may be necessary to adapt it for use with 'the particular vehicle to which vthe 'ack isto l -be'-applied.- 'I heiorganization-of suc ascre'w fwith the piston has given rise to rather a serious manufacturing problem involving difoperations and is especially undesirab e in a device tain novel features 'of the construction arrangement and combination of parts h to provide a lifting piston ofthe jack with an p and partly in centr 7 section showin the invention applied to one t 2'ia a view part1 applied to of producing a jack of this ty e-as 16w as possible if it is to be available to theordinary automobile owner. It is alsoessential that sired to move the jac from beneath the vehicle.. S rings have been proposed for this -purpose, ut ith'as been found diflicult matter to organize the springs with the piston in d a way t at will not decrease 'the range of,"

.action of the piston or impair other desirable quahties or features of the jack construction.

,One of the. principal objects of the present invention resides in the revision in ahy- -d raulic jack of a simple, re iable-andefi'ecting lifting piston extension arrangement, which is susceptible of convenient and economical manufacture and whi 'hiavoids the d'ifliculties and expense of prior "nstruction'as the ele- 1o organized and constructed as to avoid the necessity of expensive or-dificult'machinery I operations,

'ments of the extension arrangement are so- Further, the present invention proposes in s conjunction with the lifting piston extension a novel form of spring returnwhich, while 'being embodied in a simple and durable con- .structioiz:a

easily applicale to the 'jack, does not dec piston or in any way impair the other desirable qualities and features of the jack.

I Other objects andadvantages reside in cerw will be hereinafter more fully described and particularly pointed but in :the appended claims,'r3ference-fbein had to tgiehaccom ying jraw' g' ormin' aparto t isspec-. fi'cation, andin which: g igurelis a view 7 vertical longitudinal looking towards the: left of Fi re 1- and partly iii-transverse central vertical section. I

shown In the, drawing, kilnverl ltionzlixsb one .o rau'c'ac utitis to'be understog d y 1 ase'the' range of actionof the lifting a; F

ich 'ati v 00 artly in sideelevation yin front elevation as j thatjit m y bejutilize'd t q 10o equal advantage with various other types of jacks, one type being-shown merely for the sake ofillustrating, one example or embodiment of the invention. The type o'f jack illustrated is more fully shown and described in the pending application of Harry W;

Bolens, forjhydraulic jacks, 'filed July 20,

1927, Serial No. 207,129, now Patent Nofi 1,709,000, granted April 16, 1929, to whichv reference is'made-for a full disclosure of the general features of the jack construction.

As shown, the jack includes a base 1 hav- 5 cy inder 2 in which a piston 3 is fitted. The

piston has a hollow piston rod 4 secured thereto and sliding through a stufiin box 5 provided at-the upper end of the cylinder 2.

' The piston rod is made up of ordlnary tubing and re uiresn special machinery. In tlns 9 type 0% jack, the space 2a above the piston constitutes the reservoir for the liquid. A V

- manually operable pump 6 is swiveled to the base -.1,-the pump communicating throughvalve controlled passages with the interior of the lifting cylinder both above and below the iston cylinder therein, so that upon -man1pulation of-the pump 6 the liquid 1s transferred from the reservoir space 2a above the piston to beneaththe piston wherel by to force the piston up or elevate the jack.

A suitably manipulated valve controlled by;

' pass is provided between the space in the cylinder2 beneath the piston 3 and the'reservo r space 2a to permit of th return of the liquid from beneath the piston to the reservoir space 2a independently of. the pump when the j aclr is to be lowered. r

Z The hollow piston rod 4 has an extension 10 in the'forn of a rod which slidably fits 0 within the hollow piston 4. The lower end of the rod 10 is formed with a guiding portion 11 which has free guiding contact with the-interior 'of the piston 4, Above the guiding portion '11 therod is screw threaded as at 10a but these screw threads slide freely nectin member and nut 12 which-permits the extension rod to be turned to move it out of thei'mam piston ,rod to the desired extenti In any'adjustment, however, any load placed 1 on-the extension rod is transmitted directly Wthrough'its positive structure to the main plstonirod. To facilitate turning'of the "exan integral" upwardly extending lifting terminals 21 at their lower end engaged with tension rod 10 and the consequent adjustment thereof, and to better adapt the upper end thereof to engage the element or article to be lifted, a lifting head 15 is attached to the upperuend of the extension rod 10. Any desired attaching means njfay be provided for fixedly securing the lifting head 15 to the extension rod 10 and for the sake of simplicity in illustration, the extension rod 10 is shown as having a reduced and threaded end 10 engaged with an internally threaded central 1 opening 15 in the'lifting head 15.

For the 'purposeof automatically lowering the piston or lifting element of the jack when the by-pass is opened, a pair of retractile coil springs 20 are provided and as shown are disposed outside of the lifting cylinder. The springs 20 parallel the lifting cylinder 2. at its opposite sides and have hook-like apertured lugs 22 integral with the'base 1. At thcirupper end the springs 20 have hook-v like terminals 23 engaged'with the apertured lugs provided by the downwardly and outwardly extending ends of" the combined spring attaching member and nut 12. The springs 20 are under tension when thelifting element of the jack is completely lowered and tend to maintain in this position. When the lifting element of the jack is raised, the springs 20 are further stressed and tensioned and the force which these springs apply to p the combined spring attaching member and nut 12 is directly transmitted at all times to the main piston. rod 4.as'this combined spring attaching member and nut 12 always abuts against or positively engages the upper end of this main piston 'rod 4. It will be obvi-, ous from the foregoing that the springs 20 do not in any way lessen the range of action of the lifting element of the jack and as they are external of the cylinder, they do not com-' "'plicate its construction or, make it diflicult to obtain a leak proof jack. 5 While having these advantages they supplya very effective agency for lowering the lifting element of the jack at the proper time. Further, one of the elements throughwhich the springs act, that is} the element 12 also constitutes a nut with which the extension rod of the lifting element .coacts. Such a nut may be very inexpensively and conveniently produced and obviates the necessity of constructing a special type of piston rod involving difliculties inmanufacture and expense, And the springs 20 provide "the means which holds the nut 12 in position and against turning when the extension rod- 10 is rotated to .adjust its relation" to the main piston rod 4. I The invention claimed is: 125 1. A hydraulic jack including a base, a lifting cylinder carried thereby, a liftingpiston fitted in said cylinder at hollow piston rod connected to the piston and projecting exteriorly to the cylinder, a combined spring connecting member and nut abutting the upper end of the piston rod, retr'actile coil springs between the combined spring connecting member and nut and the base operating to bias the piston to its lowermost position in the c linder and to releasably hold the combine connecting member and nut against rotation and an extension member slidably fitted in the hollow piston rod and threaded through the. combined connecting member and nut. 2. A hydraulicjack including a cylinder, a'piston therein, a piston rod connected to the piston, an extension member freely interfitted' with the pistonrod and having a screw thread, a separate nut'disposed externally of the cylinder and enga ed with said screw thread and with said p ston rod and spring means coacting with the nut to hold it en .gaged with said piston rod and against rotary movement and to bias the plston and parts connected thereto to lowermost position. In witness whereof, I have hereto afi xed m 'si ature.

- \IHARRY w. BOLENS. 

